Jack base



FIG. 1 is a perspective view of a jack base showing our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a back view thereof;

FIG. 4 is an enlarged left view thereof;

FIG. 5 is an enlarged right view thereof;

FIG. 6 is an enlarged top view thereof;

FIG. 7 is an enlarged bottom view thereof; and,

FIG. 8 is a partially enlarged view of FIG. 5 .

The broken lines shown on the drawings depict portions of the jack basethat form no part of the claimed design. The additional broken lines inFIGS. 5 and 8 are to show enlarged areas and form no part of the claimeddesign.

CLAIM The ornamental design for a jack base, as shown and described.